Bad news for women who like to get their hair severely straightened with the popular Brazilian blowout technique à la Jennifer Aniston: it may look good, but apparently it’s not good for you.

The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) issued a hazard alert on April 11 warning hair salon owners and workers about potential exposure to formaldehyde from using some hair smoothing and straightening products, including the Brazilian Blowout brand. (Formaldehyde helps bind keratin to hair, straightening it.)

Responding to complaints from workers, OSHA found evidence of dangerously high levels of formaldehyde in the air of salons using these hair-straightening products — even though the products are often listed as “formaldehyde free.” The agency also found evidence of allergic reactions by workers and clients to the products, including nosebleeds and eye irritation. (More on Time.com:See photos of strange beauty pageants)

Formaldehyde has been identified as human carcinogen by many countries and scientific institutions — albeit not yet by the federal government — but as OSHA Assistant Secretary David Michaels said in a statement, employers and employees were often unaware of the risks of using these products:

Workers have the right to know the risks associated with the chemicals with which they work, and how to protect themselves. Employers need to know these risks in order to ensure the safety and health of their employees.

OSHA recommends that salon owners use products that do not contain formaldehyde, methylene glycol, formalin, methylene oxide, paraform, formic aldehyde, methanal, oxomethane, oxymethylene or Chemical Abstract Service Number 50-00-0. But that won’t always be easy for workers — personal care products sold to salons and other professional hair-care services aren’t always required to list their ingredients. “Workers may not even know what’s in the products they’re using,” says Alexandra Gorman Scranton, director of science and research at Women’s Voices for the Earth and a co-founder of the Campaign for Safe Cosmetics.

The OSHA alert comes on the heels of a legal scrum in California, where the state attorney general filed a lawsuit against Brazilian Blowout, seeking to mandate health warnings on the products. That would be the first enforcement action ever taken under the California Safe Cosmetics Act. In a memorandum filed recently in court — which you can read here [PDF] — California says that state testing has shown that Brazilian Blowout Smoothing Solution contains approximately 8% formaldehyde by weight, which “is in the range typical of embalming fluid used by funeral homes.” Just to put that in perspective, the conservative Cosmetics Ingredient Review Expert Panel, which includes industry representatives, has measures formaldehyde as safe only if it makes up 0.2% or less of a product. (More on Time.com:See the top 10 beauty pageant scandals)

Canada warned its citizens about Brazilian Blowout and similar straighteners six months ago when regulators first learned about health concerns, and the products were pulled off store shelves. The Food and Drug Administration (FDA) — which regulates cosmetics in the U.S. — hasn’t yet taken that step, though over the past several months it has begun looking into complaints about the products. An FDA spokesperson told TIME that the agency would have an update soon — we’ll update the post when that comes out.

The agency may need to act soon. A new report published on April 12 by the Environmental Working Group — a non-profit that has often been critical of the chemical and cosmetics industries — reviewed 47 unpublished “adverse event” reports filed with the FDA and obtained via the Freedom of Information Act. Salon clients and personnel reported severe allergic reactions, including hair loss, rashes, blistered scalps and other health problems. From one report:

Hair continued to fall off as she continued to rinse. Blisters also discovered on the back of head… Complainant developed severe stability problems (severe dizziness)… Physician examined and noted hair loss, blisters on scalp and ulcer formation in her mouth.

As EWG Vice President for Research Jane Houlihan told me, the potential harm from hair straighteners like Brazilian Blowout is widespread:

We surveyed 41 top salons and found that almost all of them are using hair straightening treatments. We look across the industry, and the fact is if you’re using a Brazilian-style keratin treatment, it’s almost certainly releasing formaldehyde.

The chemical industry is actually sort of coming down on the side of regulators and activist groups on the issue. The American Chemistry Council, a major trade group, last year called on the company that makes Brazilian Blowout to cooperate with government officials and ensure the product meets regulations.

John Bailey, the chief scientist with the Personal Care Products Council, a cosmetics trade group, and the former head of the FDA’s cosmetics program, told me that he’d never before seen OSHA issue a warning of this sort before the FDA had acted. He also said the the blowout seemed to be an “atypical use” of formaldehyde in cosmetic, and that an expert safety panel would be reviewing the products:

The original safety review did not take into account these type of applications… We don’t know what level [of formaldehyde] would be appropriate, or how it is delivered. It’s uncharted ground as far as formulations and amounts.

To activists, that’s the problem: regulation of the cosmetics industry is fundamentally lacking. The FDA’s regulatory powers date back to the Federal Food, Drug and Cosmetic Act of 1938 — and they haven’t been updated much since. The FDA can’t actually order a mandatory recall of a cosmetic like Brazilian Blowout, though it can request one, which is almost always followed. (It hasn’t done so yet.) In the meantime, consumers are largely dependent on the companies and industry to perform safety tests and be truthful with ingredients — and if mistakes are made, regulators are often acting after the fact.

Democratic Representative Jan Schakowsky introduced the Safe Cosmetics Act last year, which would have increased FDA regulation over the industry; the legislation went nowhere, but it will likely be reintroduced soon.

Whatever you think about cosmetics regulation, however, it’s hard to understand how a chemical like formaldehyde should be found in a hair salon. Siobhan O’Connor, an editor with Prevention magazine, tried a Brazilian blowout treatment with her friend Alexandra Spunt a few years ago, and was shocked to find that formaldehyde was the active ingredient. That began their research into the cosmetics industry, which culminated in the 2010 book No More Dirty Looks. O’Connor told me:

There’s a larger problem at issue here. In Europe, more than 1,000 chemicals have been banned for use in cosmetics, many of them carcinogens and reproductive toxicants. In the United States, only eight (or nine by some counts) substances have been restricted or banned by the FDA, because that agency is underfunded and impotent when it comes to real regulation. The system is perfectly designed to let something like the Brazilian blowout get to market without much blowback.

Speaking as someone with curly hair, I have to say, it’s just not worth it.